1. Field of the Invention
The present invention relates to a method for a surface treatment of a substrate, a substrate thus surface-treated and a dental article comprising a substrate. More specially, the present invention relates to a method for a surface treatment of a substrate such as ceramics, plastic and metal and a substrate surface-treated and more particularly to a method for a surface treatment of a dental article for use in dental treatment including prosthesis such as a metallic crown or denture and orthodontic treatment.
2. Description of the Related Art
In general, in order to bond a substrate such as ceramics, plastic and metal with using an adhesive, it is practiced to subject the substrate to surface treatment for enhancing the adhesive property thereof. Methods for the surface treatment of a substrate can be roughly divided into two known groups, i.e., dry treatment and wet treatment.
Known examples of dry treatment include blasting, flame treatment, corona discharge treatment, plasma treatment, ultraviolet treatment, laser irradiation treatment, and ozone oxidation. Known examples of wet treatment include treatment with coupling agent, and primer coating.
For example, a ceramics substrate to be used in the dental article for dental treatment, circuit board, glass for liquid crystal, photomask, etc. is often subjected to plasma treatment, ultraviolet treatment or the like so that organic materials and other materials on the surface thereof are decomposed away to improve the adhesive property thereof (see, e.g., JP-A-10-248857).
It is also known that such a ceramics substrate is subjected to blasting (method which comprises allowing an abrasive to collide with the surface of the object in the stream of pressurized air to remove foreign matters from the surface of the object) or the like so that the surface of the ceramics substrate is roughened to enhance the adhesive property thereof (see, e.g., JP-A-6-285087).
It is also often practiced particularly in the art of dentistry to subject the surface of a dental article for dental treatment to primer coating with a compound normally made of an aromatic carboxylic acid or the like called primer. In this manner, a protective layer is formed on the surface of the dental article for dental treatment, making it possible to enhance the adhesive property of the article or stabilize the surface conditions of the article (see, e.g., JP-A-2000-93436).
However, the ceramics substrate which has thus been subjected to surface treatment can adsorb organic materials and thus lose its adhesive strength with time when it is left unbonded even if organic materials have been removed by plasma treatment or ultraviolet treatment.
Further, even the substrate which has been subjected to blasting can adsorb a polar compound or the like by the area where hydroxyl groups are exposed and thus lose its surface adhesive strength when it is left untreated.
Moreover, in the case where the substrate is subjected to primer coating to form a protective layer on the bonding surface thereof, the protective layer deteriorates after prolonged storage, making it likely that the adhesive strength of the substrate can be deteriorated.
Therefore, the surface treatment, if effected for the purpose of enhancing adhesive property, needs to be effected shortly before bonding. However, it is troublesome to effect the surface treatment shortly before bonding of the substrate. Similar problems occur not only with ceramics substrates but also with plastic substrates and metallic substrates.